108 
Proceedings of Royal Society of Edinburgh. [feb. 7. 
rather more than 60 sq. cm. The curves I obtained evidently pos- 
sess, to a considerable extent, symmetry about an axis. They roughly 
resemble hyperbolas, but have rather more curvature near the vertex. 
A few of them are represented in fig. 2. Time is measured hori- 
zontally, each scale-division representing 6J minutes. The numbers 
on the vertical scale, when multiplied by 0*267, give the current- 
strength in amperes. I used in each experiment a battery of 3 tray- 
Daniell cells, the electromotive force of which remained constant 
during the experiment. The battery was coupled in circuit with a 
Helmholtz tangent galvanometer and the electrolytic cell. The 
reduction factor of the galvanometer is 0*267. The needle of the 
galvanometer ceased vibrating in about half a minute after com- 
pleting the circuit, at which time the first reading was taken. The 
following tables give the details of one experiment : — 
Deflection in Degrees at intervals of One Quarter-Minute. 
64*8, 64*4, 63*5, 62*7, 61*8, 60*9, 59*7, 58*8, 58*2, 58, 57*8, 57*4, 
57, 56*7, 56*2, 55*7, 55*2, 54*6, 54, 53*6, 53*1, 52*7, 52*4, 51*9, 
51*7, 51*4, 51*1, 50*9, 50*5, 50*3, 50, 49*8, 49*6, 49*4, 49*2, 48*9, 
48*8, 48*6, 48*4, 48*3. 
At intervals of One Half-Minute. 
47*9, 47*6, 47*3, 47*1, 46*8, 46*6, 46*4, 46*2, 45*9, 45*8, 45*7, 
45*6, 45*5, 45*3, 45*2, 45*1, 44*9, 44*8, 44*7, 44*5, 44*4, 44*3. 
At intervals of One Minute. 
44T, 43*9, 43*7, 43*6, 43*4, 43*2, 43 1, 42*8, 42*7, 42*6, 42*5, 
42*3, 42*2, 42*1. 
At intervals of Three Minutes. 
41*6, 41*1, 40*8, 40*3, 39*9. 
At intervals of Five Minutes. 
39*4, 38*7, 38*4, 37*8, 37*4, 36*9, 36*6, 36*4, 36, 35*7, 35*4, 
35T, 34*8, 34*5. 
These results are shown graphically in the curve in fig. 1. In 
each experiment the total resistance in the circuit was slightly 
different. A special feature of the group of curves in fig. 2 is the 
close parallelism of the axes. 
